1. Field of the Invention
This invention relates to a heat exchange unit for both controlling the temperature of air flowing therethrough and the humidity of the air being discharged therefrom. The system is particularly adaptable to residential air conditioning systems wherein bypass apparatus may be utilized to cause a portion of the air to flow through the heat exchanger serving as an evaporator and a portion of the air to bypass the heat exchanger.
2. Prior Art
It has been recognized in many geographical areas that proper air conditioning systems should not only lower the temperature of the space being served when the temperature therein has exceeded a predetermined level but should also decrease the relative humidity of the space as a function of the air conditioning. During a typical air conditioning operation, air from the enclosure to be conditioned is circulated over a heat exchanger. The heat exchanger absorbs heat energy from the air lowering its dry bulb temperature. If the temperature of the air is lowered beneath its dew point, then moisture from the air is condensed onto the heat exchanger surfaces and the actual amount of moisture contained in the air is reduced. Should the air to be cooled not be lowered in temperature beneath the dew point, then no water will be removed from the air and there will be no dehumidification effect. In fact, it is possible to increase the relative humidity of air being conditioned since if moisture is not removed from the air then when the dry bulb temperature is decreased the capability of the air to absorb moisture is also decreased and the ratio between actual moisture contained in the air and the amount of moisture that may be contained within the air is increased. Consequently, relative humidity can increase during the air conditioning process.
To provide for additional latent cooling it is necessary to lower the temperature of the heat exchanger such that air passing through the heat exchanger will be lowered in temperature below the dew point and moisture will be removed therefrom. One manner of reducing the temperature of the heat exchanger has been by varying the fan speed to adjust the rate of flow of air over the heat exchange surface. Reduction in flow rate allows the temperature of the coil to decrease and consequently additional moisture may be removed from the air.
Another method of lowering the temperature of the coil over which the air passes is to limit the number of circuits in the coil through which the refrigerant flows. By limiting the number of circuits each circuit has a larger refrigerant flow volume and hence is maintained at a cooler temperature. Hence, by limiting the number of refrigerant flow circuits the temperature of the coil may also be reduced such that additional moisture is removed from the air to be conditioned. Through experimentation it has been discovered that most humans are comfortable when the temperature humidity index is less than 70. Once the temperature humidity index level reaches 75, approximately half the population is uncomfortable and at the level of 80, most of the population is uncomfortable. The temperature humidity index level is determined by multiplying the sum of the wet bulb and dry bulb temperatures by a factor of 0.4 and adding 15. It is the purpose of the present invention to decrease the dry bulb temperature through the normal air conditioning process of the air being circulated to cool an enclosure and to additionally decrease the wet bulb temperature such that a combination of these two factors maintains the temperature humidity index level within the comfort range. The utilization of a bypass area and a damper to adjust the flow of air between flowing through the heat exchangers and flowing through the bypass area is utilized to attempt to achieve the combination of wet bulb and dry bulb temperatures desired to maintain the space being conditioned within the target temperature humidity index level.
As shown herein, a manual device is used for positioning a damper to apportion air flow between air flowing through the heat exchanger and being cooled and air bypassing the heat exchanger. By bypassing a portion of the air, the air flow through the heat exchangers is reduced and consequently the temperature of the heat exchanger is lowered such that additional moisture may be removed from the air passing in heat exchange relation with the heat exchanger since it may be cooled to a lower temperature. The apportionment of air between flowing through the heat exchanger and bypassing the heat exchanger allows the individual to control in each instance the operation of the indoor heat exchanger to achieve the desired coil surface temperatures and thereby to hopefully achieve the desired temperature humidity index level.
Although not a part of the instant patent application, it is further envisioned that a stepper motor or similar motion device could be utilized to regulate the position of the damper in response to a humidistat sensing the humidity level in the enclosure to be conditioned.